Electrical measuring instrument.



No. 529,130. patented July 18, I899.

sfw. JEWELL. I ELECTRICAL MEASURING mSTRUHENT.

(Application filed m 16, 1899.)

No Model-J WWwzssms:

). A dYaHu 5o 2 is a plan view of the interior of the meter UNITED STATES "PATENT OFFICE.

EDWVARD W. JEVVELL', OF CHICAGO, ILLINOIS ELECTRICAL M EASURING INSTRUM ENT.

SPECIFICATION forming part of Iietters Patent No. 629,130, dated July 18, 1899. I

A pplioationfiledMayl8,1899. Serial it); 717,321. ca model.)

To all whom/it ma sme m- Be it known that I, EDWARD W. JEWELL, a citizen of the UnitedStates, residing at Ohicago, in the county of Cook and State of Illinois, have invented a'certain new and useful Improvement in Electrical Measuring Instruments, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to an electrical meter for electrical circuits, my object being more particularly to provide a form of construction which is readily adapted toampere-meters and especially to meters for measuring very small currents, which meters are more commonly known as. milliampere meters. The features of my invention are, however, applicable to other forms of meters. It is the purpose of the present invention to provide means whereby the parts of the meter may be readily adjusted for extreme accuracy, and my invention contemplates arrangements whereby the dial-pan and mesons of the in strument may be adjusted in position.

In accordance with my invention I mount the dial-pan so that the samemay partake of a rocking movement or partial rotation relative to the body of the instrument upon which the index or pointer and the magneta re sup- I I ported, whereby the dial-pan may be moved as desired to'bring the' index'to the zero position. In assembling the parts initially it is desirable to provide a construction whereby the coils may be readily adjusted with refer-' ence to the magnet, and in accordance with p the present invention I mount the coils upon a support whereby the same may be rocked relatively to the magnet and maintained'in the adjusted position, and I further mount the coils so that the same may partake of a movement toward and from each other to thereby adjust the same relatively to the needle of the instrument to vary the stren'gthof the magnetic field to which the same is subjected. V

I have illustrated my invention in the accompanyingdrawings, in which- Figure 1 is a plan View of the meter. Fig.

nut cv to lock the plate in position.

with the scale-pan removed. Fig. 3 is a cross sectionalview of the meter. Fig. 41s a detail view of the handle for adjusting the scalepan. Fig. 5 is a partial view of the scale-pan, showing the elastic tongues thereon. Fig. 6 isa detail view of the magnet-support. Fig. 7 is a View showing the manner in which the arbor is supported.

Like letters refer to oral figures. 1

. Upon the insulating-base a is mounted a base-plate 6, held in position by a threaded shank c, which passes through the center of the plate, the lower end thereof carrying a he shank c carries a threaded bore, within which like parts in the sevfits the screw 0 carrying a jewel c in the upper end to serve as abearing. Upon the base-plate b the upright posts e e are mounted and support upon the upper end the bridge 6', which carries the jewel 6 in which rests Itheu pper end of the arbor 0 the other end being supported by the jewel 0 The arbor "carriesnear its upper end. the index d and near its lower end thepneedle c Mounted :upon the base-plate b are the spools for the windings, which consist of two parallel side plates f f, supporting a hollow shell f Upon the spools are thefwindiugs f f. The

outer side platesff carry the slotted plates f f atright angles thereto, through which pass the screws f f. By this construction the spools may be moved to any desired position and secured in position by the screws f. The posts 9 g carry upon the shoulders the s f th magnet g whic h are held in position by the washers g g carrying the fingers g g, which are bent down over the outer portion of the' magnet, and the nuts 9? g are secured upon the base.

' Surrounding the parts heretofore described is. the casing h, secured to the base by means of the screws passing up through the bottom of the base and entering the circular portions h h,'carried on the inner wallof the casing. Upon the outer wall of the casingbindingposts h h are mounted, the same being insulated from the casing. The binding-posts form the opposite terminals of the windings f f which are connected in series. Through the opening or slot 7&5 in'the casing a screw-h extends, being attached to a lug h", carried upon the lower face of the scale-pan h The scale-panh" rests upon a shoulder 7L carried on the casing It. By means of the screw it serving as a handle the scale-pan may be partially rotated to adj ustthe scale with refer ence to the index. The scale-pan is provided upon the periphery with a rim 1', having two free ends or tongues 12 i, which form springs or resilient tongues and press against the inner face of the casing to hold the pan in any adjusted position to which the same may be moved. The scale-pan has the graduations formed upon the face thereof and has a circular opening 2' at the center. Over the face of the meter is placed a glass cover, the outer edge of which fits'in a metallic rim-designed to slip over the casing.

The magnetic field generated by the windings acts upon the needle to move the index over the scale-pan. When it is desired to adjust the zero-point on the scale to the position of rest of the index, the scale-pan maybe partially rotated to the desired degree. When it is desired to adjust the strength of the field to which the needle is subjected, the screws f f may be loosened to permit the spools to be moved to adjust the strength of the field to the required degree, after which the spools may be clamped in position by means of the screws f f In assembling the partsor when it is desired to. make an adjustment of the windings relatively to the magnet the not 0' may be loosened and the base-plate b may then be partially rotated about the shank c to carry the windings to the proper position, after which the nut may be tightened to lock the parts in position.

Having described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. In an electrical measuring instrument, the combination with a casing, of magnetwindings mounted therein, and a scale-pan r'otatably mounted upon said casing independently of the magnet-windings, substantially as described.

2. In an electrical measuring instrument, the combination with a casinghaving ashoulder formed thereon, of a scale-pan supported upon said shoulder and arranged to be partially rotated to permit adjustment of the same, substantially as described.

3. In an electrical measuring instrument, the combination with a casing having a shoulder formed on the inner wall thereof, of a scale-pan restingthereon and arranged to be rotated and provided with a resilient tongue adapted to engage the casing, substantially as described.

' 4:. In an electrical measuring instrument, the combination with a casing, of a scale-pan rotatably supported thereon and carrying a rim having a portion thereof partially severed to form a resilient tongue adapted to' engage the casing, substantially as described.

5. In an electrical measuring instrument, the combination with a casing, of a scale-pan rotatably mounted thereomand a handle secured to the scale-pan and passing through a slot in the casing, whereby the scale-pan may be adjusted in position, substantially as described. v

6. In an'electrical measuring instrument, the combination with a base, of a casing mounted thereon, a scale-pan mounted upon said casing, and asupport for the magnetwinding mounted upon the base and rotatable thereon to permit adjustment relative to the scale-pan, substantially as described.

7. In an electrical measuring instrument, the combination with a pair of spools for the windings of a support upon which thesame are mounted, and means for permitting the movement of the spools toward and from each other to adjust the same, substantiallyas described.

' 8. In an electrical measuring instrument, the combination with a supporting-plate, of a pair of spools mounted thereon having laterally-extending portions provided withslots, and a screw passing through each of said slots whereby the relative positions of the spools may be adjusted, substantially as described.

0. In a meter, the combination with a sup-' porting-plate having a central shank pro= vided'with a threaded bore and athreaded exterior, of a screw fitting in said bore and carrying the journal or jewel for the arbor and a nut screwing upon the exterior of said shank to lock the supporting-plate in position, substantially as described.

10. In an electrical measuring instrument, the combination with a base, of a supportingplate having a central shank passing through said base, a nut screwing upon said shank,

and spools for the windings supported upon said plate, substantially as described.

11. In an electrical measuring instrument, the combination with a base, of a supportingplate thereon provided with a central shank extending therethrough, a nut adapted to screw upon the end of said shank, spools for the windings mounted upon said plate, and means for permitting the movement of said spools toward and from each other, substantially as described.

12. In an electrical measuring instrument, the combination with the casing, of an annular scale-pan rotatably mounted thereon, and magnet-windings independent of the scalepan and mounted Within the central opening of said scale-pan, substantially as described.

13. In an electrical measuring instrument, the combination with a base, of a casing mounted thereon, a rotatable scale pan mounted upon said casing, and a rotatable support for the magnet-windings mounted upon said base, substantially as described.

14. In an electrical nieasnring instrument, In witness whereof I have hereunto subthe combination with abase, of asupportingscribed my name in the presence of two wit- 1o plalte for the magnet-windings carrying a cennesses. tra shank passing through said base about I 5 which the plate may be rotated, and a, nut EDWARD JEWELL' fitting on said shank to hold the supporting- Witnesses: plate in an adjusted position, substantially W. CLYDE JQNES, as described. PERCY O. GILL. 

